Domain walls in spin-valve nanotracks: characterisation and applications

Magnetic systems based on the manipulation of domain walls (DWs) in nanometre-scaled tracks have been shown to store data at high density, perform complex logic operations, and even mechanically manipulate magnetic beads. The magnetic nano-track has also been an indispensable model system to study fundamental magnetic and magneto-electronic phenomena, such as field induced DW propagation, spin-transfer torque, and other micromagnetic properties. Its value to fundamental research and the breath of potentially useful applications have made this class of systems the focus of wide research in the area of nanomagnetism and spintronics. This thesis focuses on DW manipulation and DW-based devices in spin-valve nanotracks. The spin-valve is a metallic multi-layered spintronic structure, wherein the electrical resistance varies greatly with the magnetisation of its layers. In comparison to monolayer tracks, the spin-valve track enables more sensitive and versatile measurements, as well as demonstrating electronic output of DW-based devices, an achievement of crucial interest to technological applications. However, these multi-layered tracks introduce new, potentially disruptive magnetic interactions, as well as fabrication challenges. In this thesis, the DW propagation in spin-valve nanotracks of different compositions was studied, and a system with DW propagation properties comparable to the state-of-the-art in monolayer tracks was demonstrated, down to an unprecedented lateral size of 33nm. Several DW logic devices of variable complexity were demonstrated and studied, namely a turn-counting DW spiral, a DW gate, multiple DW logic NOT gates, and a DW-DW interactor. It was found that, where the comparison was possible, the overall magnetic behaviour of these devices was analogous to that of monolayer structures, and the device performance, as defined by the range of field wherein they function desirably, was found to be comparable, albeit inferior, to that of their monolayer counterparts. The interaction between DWs in adjacent tracks was studied and new phenomena were observed and characterised, such as DW depinning induced by a static or travelling adjacent DW. The contribution of different physical mechanisms to electrical current induced depinning were quantified, and it was found that the Oersted field, typically negligible in monolayer tracks, was responsible for large variations in depinning field in SV tracks, and that the strength of spin-transfer effect was similar in magnitude to that reported in monolayer tracks. Finally, current induced ferromagnetic resonance was measured, and the domain uniform resonant mode was observed, in very good agreement to Kittel theory and simulations

Tourism and technology

Journeys for religious reasons has been occurring along the evolution of humanity, in more recent decades, some of these travels were motivated only by (religious) tourism reasons. The information and communications technologies (ICTs) has had much impact on tourism over time, because information is one of the most important aspects to consider in the tourism sector. ICT can contribute to greater and better dissemination of knowledge about tangible and intangible heritage, while potentiate the acquisition deeper knowledge by the tourist (or local). The sharing and dissemination of the heritage (religious) knowledge in general should nowadays be focus in all kind of users, from residents, to "traditional" tourists, including tourists with accessibility limitations, hearing and/or visual impairments, restricted mobility, etc., and special groups, like senior citizens and kids. In this context, this paper presents a methodological referential for the development of a system (application) that enhances the increase in tourist affective immersion with the displayed heritage and promoting his/her tourist experience, in a personal and spiritual level.info:eu-repo/semantics/publishedVersio

Paradigms and Approaches in Educational Research

This article aims to discuss the concepts of paradigms and approaches in educational research. It is a literature review based on the significant and recognized books on the subject. The results indicate that at least three main paradigms are used in educational research and that the basic approaches are quantitative, qualitative, and mixed methods

Referencial para a caracterização de websites de hotéis de acordo com as necessidades dos consumidores

Online presence is essential for tourism organisations, and the quality of websites can influence customers. In the case of hotels, there are many studies to evaluate website performance based on functionality, usability and other factors, much less on the amount of different information available to the consumer. In the near future by using Big Data it is expected that hotel websites will be dynamic, they will adapt themselves on-the-fly, showing personalized information to each consumer. Different consumers will have different websites (information? available) from the same hotel. This paper presents a framework for the characterisation of hotel websites, focusing on the amount of information available to the consumer in each website, which was applied in a case study during the last months of 2013 to the websites of five-star hotels that operate in the tourist region of the Algarve, Portugal. The framework allowed to identify a set of exhaustive indicators for hotel website characterisation, which were then grouped into ten fundamental information dimensions. These dimensions further fell into four dimension groups. Finally, it is presented and discussed quantitative and qualitative evaluations, that illustrates which indicators and dimensions are more often considered on hotel websites to satisfy the consumer?s information needs

Active methodologies and digital technologies: In defense of a de-centered pedagogy

The aim of this article is to explore how active methodologies and digital technologies can foster a more active participation of students in their learning process and suggests possible changes in pedagogical practices. Blended learning, conceived in a stricter sense as the mix of face-to-face and online activities, and in a broader sense as the mix of different methodologies and spaces, is considered the future of educational activities. The following methodologies are discussed: flipped classroom, peer instruction, problem-based learning, project-based learning, and game-based learning. Research shows that these methodologies, when adequately combined with information and communication technologies, result in greater motivation and involvement of the students. Although these strategies do not generate improvement in immediate retention of knowledge, more complex skills are developed when compared to traditional education methods, such as: problem solving, the transfer of knowledge to reality, and retention of knowledge in the longer term. The article concludes with a critique of the contemporary discourses that position the student at the center of the teaching and learning process, claiming for a de-centered pedagogy, in which students interact with each other, teachers and other actors, in collaboratively groups where there is no need for a center, or in which each of these actors can alternatively perform a central function